Smith-Magenis Syndrome and Sleep


Smith-Magenis syndrome (SMS) is a developmental disorder affecting about 1 in 15,000 kids. Symptoms of SMS vary widely, but children with it often have intellectual disabilities, behavior challenges, and sleep problems.

Sleep issues are very common with SMS, starting at a young age. People with SMS can have lots of trouble falling asleep, staying asleep, and waking up frequently. They tend to get less sleep than others their age. SMS also increases the risk of hypersomnia (excessive sleepiness) and circadian rhythm disorders.

So sleep difficulties in many forms are a major part of Smith-Magenis syndrome. Whether unable to fall asleep, waking repeatedly at night, or general sleep deprivation, disrupted and inadequate sleep is connected to this disorder. Managing these sleep deficits is an important part of coping with SMS.

What Is Smith-Magenis Syndrome (SMS)?

Smith-Magenis syndrome is a rare genetic disorder that is present at birth. It’s caused by an abnormality in a person’s chromosomes – the DNA-containing structures that have our genes.

Most often, SMS happens when a piece of one chromosome is missing, resulting in the loss of the RAI1 gene. Less commonly, SMS occurs due to a mutated version of the RAI1 gene rather than the gene being totally absent.

Even though SMS can be inherited, most people with it have no family history of the disorder. In these sporadic cases, SMS is usually from “de novo” genetic changes that arise randomly in the parents’ reproductive cells or in the developing embryo itself.

So while it can be passed down, most of the time Smith-Magenis syndrome strikes without being carried in the family’s genes beforehand. But in all cases, it stems from irregularities in the chromosomes and linked genes.

Smith-Magenis Syndrome
Smith-Magenis Syndrome

Characteristics of Smith-Magenis Syndrome

People with Smith-Magenis syndrome (SMS) share certain physical features, behavior issues, developmental delays, and sleep problems. But symptoms vary widely in severity.

As kids with SMS grow up, they often develop:

  • Distinct facial features like a broad face and protruding jaw
  • Broad, short hands
  • Missing permanent teeth

These traits may not be noticeable until school years, delaying diagnosis.

Most people with SMS miss childhood development milestones and have lifelong intellectual disability. Early signs include less crying or babbling as infants and missing growth markers. Delays in language and movement skills often emerge during early childhood.

Despite this, people with SMS tend to have charming, affectionate personalities and remember people and places well. But SMS also commonly involves mood issues, anxiety, trouble socializing, tantrums, attention difficulties, impulsivity, and repetitive behaviors like rocking.

Other common symptoms are short height, scoliosis, sound sensitivity, throat abnormalities, vision issues, high cholesterol, and constipation. Less common are seizures, immune problems, cleft lip, and heart, thyroid, kidney or urinary tract disorders.

So while there are shared SMS traits, the mix of developmental, physical and behavioral symptoms shows significant variation between individuals. Monitoring a child’s ongoing development is key to determining if SMS testing may be warranted.

How Does SMS Affect Sleep?

People with Smith-Magenis syndrome (SMS) typically have lifelong sleep issues. As babies they may be sleepy in the day and take long naps. Later on, children and adults with SMS tend to sleep less than peers and wake frequently at night.

Many people with SMS wake very early in the morning and feel excessively tired during the daytime. They also often spend less time in REM sleep with dreams compared to others their age.

These sleep disturbances likely stem from shifted circadian rhythms – the roughly 24-hour cycles that drive functions like sleep/wake times. The circadian disruption qualifies many SMS patients for diagnoses like hypersomnia or circadian rhythm sleep disorders.

Specific circadian rhythm issues in SMS include:

  • Advanced sleep-wake phase disorder – early morning waking
  • Irregular sleep-wake rhythm disorder – unpredictable sleep periods
  • Non-24-hour rhythm disorder – sleep time shifts steadily later daily

Younger kids may be more active at night. As adults, SMS patients often have more trouble preparing for bed and falling asleep in the evenings.

And poor sleep correlates with worse daytime behavior in SMS. So managing sleep issues is key for also coping with related behavioral challenges.

Causes of Sleep Disorders in SMS

Experts believe the sleep issues in Smith-Magenis syndrome (SMS) stem in part from the missing or mutated RAI1 gene. Though still under study, RAI1 may help regulate circadian rhythms, brain growth, and development of facial bones.

One key circadian cycle thrown off is melatonin release. Melatonin makes people sleepy and helps control natural sleep/wake patterns. Typically melatonin rises at night then decreases with morning light exposure.

But for up to 95% of SMS patients, this cycle is flipped – they have high melatonin levels during the day and low levels at night. The biological clock in their brain that governs circadian rhythms likely drives this dysregulation.

Interestingly, not all circadian cycles appear disrupted in SMS. So while the reversed melatonin production plays a major role, additional factors like melatonin resistance may contribute to abnormal sleep as well.

In summary, the loss of RAI1 impacts circadian regulation and alters melatonin release in SMS patients. This results in a tendency for daytime sleepiness and nighttime insomnia. Ongoing research aims to clarify all the drivers of sleep disturbances tied to Smith-Magenis syndrome.

How Doctors Treat SMS

Treatments for Smith-Magenis syndrome (SMS) target symptoms rather than the underlying genetics since the causal gene changes are present throughout the body.

Depending on an individual’s needs, people with SMS may benefit from medications and supportive services like therapy and special education. Treatments often address complications like attention deficits, epilepsy, constipation, vision/hearing issues, etc.

Helpful services can include early intervention programs, speech/occupational/physical/behavioral therapy, and job training.

Treating sleep problems in SMS is challenging due to minimal research. Doctors typically need to trial different medications and see how a patient responds regarding improved sleep and any side effects.

Some options include melatonin supplements, tasimelteon (which mimics melatonin), and beta-blockers to reduce daytime melatonin release. Combining morning beta-blockers with evening melatonin is one approach.

Good sleep habits are also recommended – consistent bedtime routines, bedrooms designed for night wanderings, and sleep apnea monitoring.

The goal is balancing medications with lifestyle changes to best manage symptoms including lifelong sleep deficits common to Smith-Magenis syndrome.

Living With SMS

There are a few key ways caregivers and family can support someone with Smith-Magenis syndrome (SMS):

  • Become an SMS advocate. Ask questions, request accommodations, and track medical history. Advocating benefits both patients and loved ones.
  • Schedule annual doctor visits to ensure appropriate care and referrals. Check-ups monitor development, watch for complications, and get help as needed.
  • Celebrate milestones and focus on the person’s strengths and abilities. This builds self-esteem and independence.

Respite care and breaks are also important for SMS caregivers. Connecting with advocacy groups can provide resources, support, and community. Hearing others’ experiences helps both patients and families.

The overall focus should be empowering the person with SMS while making sure their medical and support needs are fully addressed. This comprehensive approach lends help and encouragement through the lifelong journey with the disorder.

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  • Milly

    Milly is a mechanical engineer residing in Canada who loves to disassemble and rebuild the latest tech in her spare time. Her passion for understanding how electronics work combined with her engineering expertise allows Milly to provide in-depth,nuts-and-bolts reviews on everything from smartphones to high-end TVs.

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